Sand-blast machine



VNov. 2 ,1926.

H. F. HoEvEL SAND BLAST MACHINE Filed Deo. 221,v 1921 INVENTOR. ge/'maza//faeae/ m, @MM2/L www@ ATTORNEYS.

Patented Nov. 2, 1,926.

UNITED sTATEs HERMAN E'. HOEVEL, OF NEV YORK, N. Y.

SAND-BLAST y MACHINE.

Application led December 24, 1921. Serial No. 524,627.

My invention relates to machines for delivering sand or other materialfrom a tank tothe place of use, and has particular reference to machinesof the type in which a compressed medium such `as compressed air isadmitted periodically to a chamber containing the sand or like material,Jfor the purpose of causing such material to be eX- pelled from suchchamber.

An example of my invention is illustrated by the accompanying drawings,in which Fig. 1 is an elevation of the apparatusgFig. 2 is a verticalsection;y Figs. 3 and 4 are diagrammatic vertical sections showing twodifferent positions of certain cocks or valves.

`The interior construction of the blasttank may be of a well-known type,as shown in Fig. 2, where the tank 10 comprises a hopper 11 to receivethesand or other material through a screen 12, an upper compartment 13,and a lower compartment 14 from the outlet 15 of which the sand passesto the blast-pipe 16 which delivers a mixture of air and sand to theplace-of use through a pipe or hose (not shown). Compressed air issupplied to the chamber 17 containing` the blast-pipe 16, in anysuitable manner, for instance by a pipe 18, and a pipe 19 connects thesaid chamber 17.with the upper portion of the lower compartment 14, sothat thefsame pressure will prevail in said compartment and in saidchamber. A downwardly-opening spring-pressed valve 2O controls theconnection of the hopper 11 with the upper compartment 13, and a similarvalve 21 controls the connection of said vupper compartment with thelower Vcompartment 14. The upper compartment is also'adapted to beconnectedalternately, at suitable intervals of time, with the outsideair and with a source of compressed air respectively. l

According to the form of my invention .illustrated herein, thisalternate connection of the upper compartment is'effected by thefollowing arrangement and mechanism: KFrom the pipe 18 a branch conduit22 carries the compressed air to the port 23 of a casing 24, said portregistering at times (Fig. 3) with the passage 25 of a plug 26 mountedto turn in said casing. The passage 25 is adapted to register at thesame time with another port 27 of said casing 24, this portcommunicating with a conduit 2,8. The latter is connected with the uppercompartmentK 13 either directly or, as shown, by means of the upperportion of a pipe 29 communicating with said compartment at 30. A cockor valve is thus provided to control the connection of thecompartment 13(through the pipe- 28) compressed air (through the branch conduit- 22).The lower portion of the pipe 29 has a valve-controlled orcock-controlled connection with the outside air as follows: The lowerend of said pipe connects with the upper port 31 of a casing 32 in whichis mounted to turn a plug 33v having a passage 34.l The casing 32 alsohas another port which isopen to the outside air either directly orthrough al short pipe 36. In one position (Fig. 4) the passage 34registers withpboth ports 31 and 35, and the valve thus being open,communication `is established between the compartment 13 and the outsideair, the pipe 29 thus forming a ventpipe; in the other position (Fig.3), the valve is closed, that is to say, the compartment 13 has noconnection with the outside air. It will be noted that both valves orwith the source of cocks are of the very simple one-way construction,and, for the reasons explained below, this is a great advantage,particularly in regard to the valve 'controlling the connection of thecompartment 13 with the outside air. At no time are yboth plugs 26, 33in the open position.

The proper operation of thev valves requires that when either of them isopen, the other should be closed. To accomplish this automatically, Ihave provided the `tollowing mechanism, in the particular embodimentillustrated: The two movable members or plugs 26, 33 are connectedrigidly with parallel arms 37,38, respectively, onel of which, 37, has a.pivotal connection at 39 with an `operating rod orbar 40 having ahandleY 41. The bar 40 also has an upright slot 42in which is adapted toslide-a pin 43 on the arm 38, said pin being as far from the plug 33 asthe connection 39 is from the plug 26. The rod or bar 40 is mounted toslide in a stationary guide 44, in which it can also rock slightly. Itwill be understood that the axes about which the plugs 26, 33, turn, andthe connections 39, 43, are parallel to each other. W

So far as described above, theapparatus will operate as follows: Let usassume that the valves are in the position shown in Fig.

3, thus admitting compressed air to the upper compartment 13, andpreventing the escape of such air therefrom to the outside, since thevalve plug 33 shuts off communication from said compartment to theoutside air. The compressed air in compartment 1,3 also holds the valve2O closed, so that at this time no sandcan pass to the said compartmentfrom the hopper 11. The pressure of the air in compartment 13 now beingthe same as in the lower compartment 14, the weight of the sand incompartment 13 will open the valve 21 so that a charge of sand will betransferred from the upper compartment to the lower compartment, fromwhich it is fed, continuously, to the blastpipe 16. After a certainlapse of time, the rod 40 will loev operated to shift the valve plugs26, 33 to the position shown in Fig. 4, thus stopping the supply ofcompressed air to the upper compartment 13, and connecting thiscompartment with the outside air 'through the vent-pipe 29. Since the.lower compartment 14 is always connected with the supply of compressedair, it follows that the valve 21 will now be held closed tightly, sothat no sand will pass at this time from the compartment 13 to thecompartw ment 14. On the other hand, since atmospheric pressure nowprevails both in the hopper 11 and in the upper compartment 13, thevalve 20 will be opened by the weight of the sand which has previouslyaccumulated in the hopper l1, so that the upper compartment will receivea new charge of sand. It will be understood that, as usual in apparatusof this type, there is preferably a continuous Supply of sand to thehopper 11. at such a rate that a suiiicient charge accumulates thereinbetween successive openings of the valve 20.

At such times as the compressed air escapes from the upper compartment13 to the outside air immediately after the plug 33 has taken theposition Fig. 4, some dust and frequently some sand, will reach thevalve plug 33 and its seat, and on account of this, these parts willwear out quicker, and require renewal oftener than the plug 26 andcasing 24, which it will be noted are not in the. path of the dust andsand that may escape with the air at the time communication isestablished between the compartment 13 and the outside air. A veryhigh-grade cock may therefore be employed at 24, 26, since its renewalwill hardly ever be required. As stated above, the parts 32, 33constitute a one-way cock of the usual very simple and inexpensiveconstruction, and I may employ at this point (32, 33) a cheap grade ofcock so that the cost of renewal will be low.

As I have mentioned above, the rod 40 should be operated periodically toeffect a reversal of the positions of the valve plugs 26, 33. In orderthat'the attendant may be informed of the proper times for effectingthis reversal, I have shown a time-indicator connected operatively withsaid rod and constructed as follows: The bar or rod 40 has a projection45 the upper end of which is connected by a link 46 with a rack bar 47sliding in stationary guides 48, the teeth of said rack bar being inmesh with a gear wheel 49, operatively connected with a sand-glass 5U,for instance by mounting said sand-glass directly on said wheel, or onsome part, such as a support 51, connected with the wheel rigidly. Inany event, the connection of the rack bar 47 with the sandglass is suchthat at each operation of the bar or rod (whether to the right or to theleft), the sand-glass will be turned over to bring its lower (full) halfback to the upper or starting position. The time required for thepassing of the sand from the up per half of the sand-glass to the lowerhalf may be, for instance, ten minutes. In this case, ten minutes afterevery operation of the rod 40, the operator will find that the upperhalf of the sand-glass is empty, and this will remind him it is time foragain operating said rod. It will be understood that at one operationthe rod 40 will be moved toward the left, at the next operation (say,ten minutes later) it will be moved toward the right, and so on inregular alternation. Stops 52 adjustable lengthwise on the rod 40, mayvariably limit its motion in either direction.

Various modications may be made without departing from the nature of myinvention as set forth in the appended claims.

I claim:

1. A pressure tank for sand-blast apparatus and the like, a device forcontrolling the alternate connection of a chamber of the tank with theoutside air and with a source of gaseous medium under pressure, asandglass, and means, operatively connected with said controllingdevice, for inverting the sand-glass. y

2. A pressure tank for sand-blast apparatus and the like, separate cockshaving plugs to turn about parallel axes and controlling the connectionof a chamber of said tank with the outside air and with a source ofgaseous medium under pressure respectively, parallel arms connectedoperatively with said plugs, a rod attached to said arms loosely byconnections which compel said arms to remain substantially parallel toeach other but permit the rod to change its inclination, and astationary guide in which said rod has both longitudinal and rockingmobility.

3. A pressure tank for sand-blast apparatus and the like, a device forcontrolling the alternate connection of a chamber of the tank with theoutside air and with a source of gaseous medium under pressure, alongitudinally movable rod for operating said controlling device, a rackconnected with said rod, a support mounted to turn and operated by saidrack, and a sand-glass carried by' said support and inverted by themovement thereof.

4. A pressure tank for sand-blast apparatus and the like, separate cockshaving plugs mounted to turn, and controlling the connection of achamber of said tank With the outside air and with a source of a gaseousmedium under pressure respectively, arms con` nected operatively andpositively with said plugs and mounted to rock, and a movable actuatingrod positively connected with both of said arms to impart a simultaneousroeking movement to such arms and to the plugs connected therewith topositively rock said plugs to and from their open and closed positions.

5. In a sand blast apparatus, a tank having a pair of compartments,valve means movable to two different positions, in one of which agaseous medium under pressure is admitted to one of said compartments,and in the other of which the gaseous medium is shut off from saidcompartment and the outside air is admitted thereto, and an indicatingldevice operatively associated with said valve means for movementtherewith to indieate the expiration of the normal maximum period oftime said valve means should remain in either of said positions.

In testimony whereof I have signed this specification.

HERMAN F. HOEVEL.

